Copyright 1999 by The Gerontological Society of America
Journal of Gerontology: SOCIAL SCIENCES
1999, Vol. 54B, No. 1, S31-S40
Trends in Health and Ability to Work Among the Older
Working-Age Population
Eileen M. Crimmins,1 Sandra L. Reynolds,2 and Yasuhiko Saito3
1
Andrus Gerontology Center, University of Southern California, Los Angeles.
2
University of South Florida, Tampa.
3
Nihon University, Tokyo, Japan.
Objectives. Because of recent changes in Social Security regulations that will soon begin to raise the age of eligibility for full retirement benefits, it is important to determine whether health and ability to work at older ages have improved in recent years.
Methods. Individual-level data from the National Health Interview Survey from 1982 through 1993 are used in this
analysis. Trends in self-reported ability to work, presence of disease, and causes of actual work limitation are examined.
Results. Men and women in their 60s, that is those in the older working ages and younger retirement ages, report
significant improvement in their ability to work. The change in work ability is large enough so the percentage unable to
work at age 67 in 1993 is lower than the percentage unable to work at age 65 in 1982. This improvement appears to
have been similar for racial and ethnic groups and across educational subgroups of the population, although African
Americans and those with lower educational attainment are less healthy to begin with. The improvement in health is
due to the changing educational composition of the population, which is linked to better life-long health, different occupational circumstances, and better health behaviors. In addition, the improvement in work ability is explained by decline in the prevalence of cerebro/cardiovascular diseases and arthritis.
Discussion. The level of observed improvement in work ability means that the legislated rise in age of full eligibility for Social Security benefits should be more than compensated for by the improved ability to work.
T
HE increase in the age at which full Social Security
benefits are first payable to retired workers and the reduction in benefits at early-retirement ages legislated by the
1983 Social Security Amendments were based on the assumption that decreases in mortality over the preceding
decade had been accompanied by improving health among
the older working-age population. The assumption was that
increases in life expectancy would result in increases in
disability-free life expectancy and, thus, that normal retirement age could increase accordingly, reaching 67 for parts
of the baby boom cohort. The appropriateness of these assumptions was questioned at the time because evidence of
deteriorating health among the older working-age population during the 1970s was presented at the hearings preceding passage of the amendments (Feldman, 1983). There is
some recent evidence, however, that health and the length
of disability-free life have been improving since the 1980s
among some age groups (Manton, Corder, & Stallard,
1993, 1997; Crimmins, Saito, & Ingegneri, 1997). If health
and ability to work among those in the later working ages
and early retirement ages are improving, increasing the age
of full eligibility for Social Security will impose fewer
hardships on older workers.
This article investigates trends in health and work ability
among the older working-age and early retirement-age
population—those aged 50 to 69—during the 1982 to 1993
period. Three questions are addressed: Is there evidence of
improving work ability in the older working and early re-
tirement ages? Are any trends in work ability the same for
subgroups of the population? Can any trends be explained
either in terms of the composition of the population or the
prevalence of underlying health conditions?
Background
Mortality, health, and disability.—Since the passage of
the Social Security Amendments, much has been learned
about health for the older working-age and younger retirement-age population that makes it clear that one cannot
equate mortality change and health change in making policy. For instance, we know that mortality and disability do
not have the same causes (Verbrugge, 1989). About half of
disability is caused by conditions that are not lethal, such as
arthritis and back problems (Crimmins & Pramaggiore,
1988). We also know that during any given period, life expectancy and population health do not have to change in the
same direction. Depending on whether increased life expectancy arises from later onset of ill health or the lengthened survival of those with health problems, it is possible to
have both lengthening life expectancy and worsening population health (Crimmins, Hayward, & Saito, 1994).
The distinctions between heafth and disability have also
become clearer in recent years. Disability, or inability to
perform a social role such as work, results from underlying
health conditions including the presence of diseases, conditions, impairments, or functioning difficulties (Verbrugge
S31
S32
CRIMMINS ETAL.
& Jette, 1994). Disability, however, is affected by external
circumstances as well as health characteristics internal to
individuals. Work disabilities can be affected by the characteristics of jobs, the workplace environment, workplace attitudes, and policies toward disability as well as intrinsic
health circumstances.
Trends in health and disability.—A number of studies
have addressed change in health during the 1969-1981 period for the middle-aged and older populations using data
from the National Health Interview Survey (NHIS). The
general conclusion of these studies is that self-reported
health and disability status deteriorated between the late
1960s and the late 1970s (Verbrugge, 1984; Colvez & Blanchet, 1981; Crimmins, 1987; Yeas, 1987a, 1987b).
Researchers who have attempted to look at health and
disability change since the beginning of the 1980s report
that health seems to be improving. Using the Current Population Survey from 1962 through 1984, Wolfe and Haveman
(1990) find a period of deterioration in health followed by
improvement beginning around 1980. Waidmann, Bound,
and Schoenbaum (1995), using data for 1982-1988, report
improved health in the 1980s for broad age groups of the
adult population. Crimmins, Saito, and Ingegneri (1997) report an increase in the length of disability-free life expectancy between 1980 and 1990. Manton and colleagues
report a decrease between 1982 and 1994 in the prevalence
and incidence of disability and in the prevalence of disease
in the National Long-Term Care Survey population aged 65
and older (Manton et al., 1993, 1997; Manton, Stallard, &
Corder, 1995). Crimmins, Saito, and Reynolds (1997) also
report a decrease in the incidence of disability between 1984
and 1990 among those older than 70 from Longitudinal
Study of Aging data.
Health and disability differentials.—At the time of the
hearings addressing the changes in the age of eligibility for
Social Security, a number of persons expressed concern that
some subgroups of the population would be unduly disadvantaged by such an age increase. This concern has been justified
by the recognition of currently large socioeconomic differences in both mortality and health during the working ages
(House, Kessler, Herzog, Mero, Kinney, & Breslow, 1992;
Rogot, Sorlie, & Johnson, 1992; Wolfe & Haveman, 1990),
and the apparent widening of mortality differentials by socioeconomic status in recent years (Elo & Preston, 1994;
Feldman, Makuc, Kleinman, & Cornoni-Huntley, 1989).
Given the strong relationship between socioeconomic
status and health, it is not surprising that race and ethnicity
are also strongly related to health and disability (House et
al. 1992; Kington & Smith, 1997; Wolfe & Haveman,
1990). Differential trends in health are suggested by the
findings of Wolfe and Haveman (1990), who indicate a
stronger effect of education on disability in the 1980s than
earlier as well as different trends for racial groups.
Gender clearly influences the level of reported disability
and the pathologies and impairments associated with reported disability at any given time (Verbrugge, 1984). Past
trends have not always been identical for women and men
(Waidmann et al., 1995; Wolfe & Haveman, 1990).
Explanations for trends in health.—There has been little
systematic explanation of health trends. Increases in disability during the 1970s have been loosely attributed to the
"failure of success" argument ascribed originally to Gruenberg (1977); that is, the increasing survival of people debilitated by disease or at risk of accumulating other pathologies or impairments has resulted in worsening population
health. Not all analysts, however, are convinced that work
ability actually deteriorated over the 1970s; some have attributed the observed disability trends to increased accommodation to illness, more liberal disability benefits, or increased awareness of pathology because of more medical
care usage (Bailey, 1987; Crimmins & Ingegneri, 1993;
Verbrugge, 1984).
The two most quantitative analyses of the determinants of
past change in disability agree that both changing levels of
pathologies and impairments and behavioral reactions to
these changes are important explanatory variables (Chirikos,
1986; Wolfe & Haveman, 1990). Both of these analyses attempt to use a combination of cross-sectional and timeseries data to evaluate the factors responsible for trends;
however, both suffer because many of the concepts of interest, including the presence of disease and impairment, are
not measured or well indicated in the data sets used.
Trends in population health may also be affected by
changing population composition. Although Wolfe and
Haveman (1990) found this to be relatively unimportant
during the period they studied, it is possible that it could
become more important during a time of greater compositional change or for narrower age groups than those used in
their study. For example, over time the population has generally become wealthier, better educated, more likely to
hold white-collar jobs, less exposed to childhood diseases,
less exposed to dangerous health practices, and more exposed to health care. Compositional change could affect
both the underlying health of the population and the environment in which work takes place.
These results suggest that a new look at trends in health
and work ability among the older working-age and retirement-age populations is warranted. It is possible that health
and work ability have begun to improve in the last decade,
but more extensive analysis is needed to document this for
the age group entering retirement. Most of what has been
done has been based on only a few years of data or has
been done for either older or extremely broad age groups,
or has used indicators of health or disability that may not be
relevant to ability to work. In addition, little is known about
differential trends or causes of such trends.
METHODS
Data
Data for the analysis come from the National Health Interview Survey (NHIS) for ages 50-69 for the years from
1982-93. The NHIS is an annual, ongoing, household survey designed to monitor health and health care utilization
of the noninstitutionalized population of the United States.
Data are collected under the auspices of the National Center for Health Statistics (NCHS). The annual sample size is
about 20,000 adults in the 50-69 age range.
TRENDS IN HEALTH AND ABILITY TO WORK
In 1982, the NHIS questionnaire underwent major revisions to the questions used to monitor population disability
and health, which makes any time-trend analysis crossing
the 1981-82 line very difficult; however, since 1982 the
questionnaire has not been changed significantly, so analysis of the 1982-1993 period is now possible. Changes to
the questionnaire between 1981 and 1982 were particularly
important for determining work ability for the entire population in the retirement ages. Before 1982, respondents declared their usual activities and were then asked about limitations in those activities. Since 1982, all persons younger
than 70 years of age have been asked about their ability to
work and limitations in their work ability (National Center
for Health Statistics, 1985). These questions allow each
person to be classified as "unable to work because of
health," "limited in amount or kind of work because of
health," or "not having any health-related work limitation."
The redesign of the questions has been important in standardizing the point of reference across the population. Before 1982, comparing trends for men and women was difficult because the only universally asked questions on disability
in the NHIS referred to limitation in "normal activity," which
may differ by gender. In addition, the questions are now similar for respondents both in and out of the labor force, which
was not true in the past.
In order to monitor disease prevalence, information on the
presence of diseases and impairments is also collected from
NHIS respondents. Not all respondents are asked about all
diseases, but each respondent is asked questions about the
presence of common diseases and impairments of one body
system out of six (e.g., the circulatory system, the respiratory
system). This feature of the survey places important limitations on the analysis because the potential presence of all the
conditions and diseases affecting any individual is not
known; information is available about only one body system.
However, information on the major diseases causing any
health-related work limitation is collected from all respondents. This provides information on the existence of diseases
severe enough to cause actual work disability. The NHIS also
includes information on race and ethnicity, educational attainment, labor force status, and occupation of respondents.
Methods
Annual time trends.—Time trends in work ability and
work limitations are examined for the 12 years from
1982-1993 for age-sex subgroups of the population 50-69
years of age (divided into 12 subgroups: aged 50-54,
55-59, 60-61, 62-64, 65-66, 67-69 by sex). The subsetting into age groups is done in order to decompose the age
range into preretirement ages and ages when retirement
takes place now and is likely to take place in the future.
The question of whether there is a time trend in an agesex subgroup is answered using the coefficient resulting
from the regression of the percentage unable to work because of health (or the percentage suffering any work limitation—including inability to work) on a variable indicating
years since 1982. The specification is
p = a + b{t) + e,
S33
where p is the percentage unable to work in a given year, t
is years since 1982 (f = 0 . . . 11 in our analysis), and b is
the annual average change in percent unable to work representing a linear time trend. The similarity of trends across
11 subgroups for each age-sex group (by race and ethnicity,
education, occupation, and labor force status) is also examined in this way.
After this initial analysis of trends in grouped data for
subgroups of the population, an analysis of individual-level
data pooled over 12 years is performed to estimate the trend
in the absence of compositional changes, the effect of compositional changes, and the size of subgroup differences in
inability to work or work limitation. This pooled data set
has a total TV of about 227,000. This analysis takes the form
where P is the probability of being unable to work and Xj is
a vector of independent variables including years since
1982, age, sex, Black, Hispanic, years of completed education, labor force status, and occupation divided into three
categories (professionals/managers, laborers, and other). Interaction terms are also included where appropriate. Examination of the time trends in disease prevalence is performed
for individual diseases using the portion of the sample responding to questions on selected diseases; finally, we analyze limitation in work ability caused by specified diseases
for the entire sample.
RESULTS
The regression coefficients representing average annual
change between 1982 and 1993 in the percentage reporting
work inability for each age-sex group between age 50 and
age 69 are shown in Table 1. In later years both men and
women older than the age of 61 are less likely to report inability to work. Except for women aged 55-59, the trend is
not statistically significant for younger age groups. The size
of the annual average decline in inability to work is in the
.4-.7 range for men in the three older age groups and .5-.7
Table 1. Regression Coefficients From OLS Regression
of Percent Unable to Work and Percent Limited
in Kind/Amount of Work on Years Since 1982
(1982-1993, n=\2Y
Age (yr)
Men
Women
% Unable to Work
50-54
.06
55-59
-.03
60-61
-.08
62-64
-.38*
-.71*
65-66
-.55*
67-69
% Limited in Kind/Amount of Work (inc. Unable)
50-54
-.05
-.18
55-59
60-61
-.35*
62-64
-.45*
65-66
-.89*
67-69
-.55*
"Data are from 12 years of the National Health Interview Survey.
*p < .05.
-.04
-.17*
-.33
-.52*
-.53*
-.71*
-.06
-.15
-.32
-.47*
-.41*
-.73*
CRIMMINS ETAL.
S34
for women. The average decrease in any work limitation is
usually similar to the average decrease in complete inability. Because being unable to work is a subset of any work
limitation, the change in total limitation is really concentrated in the "ability to work at all" category.
To examine differential trends, we provide the average
annual change in the percentage unable to work for race
and education groups and for those not in the labor force in
each age-sex group. For those in the labor force and for occupation subgroups, we show average annual change in the
percent with work limitation. Table 2 contains the average
annual change in the percentage unable to work estimated
from 132 regression models. Generally, both Whites and
Blacks older than 61 have experienced significant improvement in work ability indicated by a decrease in the percent
unable to work. Among Hispanics, there has been decrease
in disability over time for many age groups but not at a significant level. Of course, the Hispanic analysis is based on a
much smaller sample size than those for the other ethnic
groups and is thus more subject to statistical fluctuation.
Trends within educational groups in a given age group
are generally similar but in many cases are not statistically
significant. Among people in their 60s, all educational
groups generally experience decline in work inability, with
the largest declines often reported among those with the
least education. Among adults in their 50s, there are no educational groups with significant decrease in work inability;
among men with the lowest education and women with the
highest education, there is some increase in disability.
Dividing the sample into those in and out of the labor
force indicates that it is people out of the labor force who
have experienced improved ability to work. Men in each
age group who are out of the labor force experience a significant reduction in inability to work. Among men in the
labor force, only those ages 60-61 experience a significant
improvement in work ability. The pattern is fairly similar
for women; those out of the labor force who are older than
61 experience improvement in work ability. The only significant change among those in the labor force is a decrease
among women 62-64 in work limitation. This change
among those out of the labor force must mean that healthier
people are retiring in more recent years.
In general, there are few significant trends in work limitation in any of the occupational categories. This means
that generally the lack of change among all workers is similar and not the result of differential trends by occupation.
Given the knowledge that trends differ mainly by age and
labor force status but generally not by sex, race/ethnicity,
education and occupation, we perform an individual level
analysis to examine the effect of each of these independent
Table 2. Regression Coefficients From OLS Regression of Percent Unable to Work (or Work Limited for Current Workers)
on Years Since 1982 for 11 Subgroups of Each Age-Sex Group (1982-1993, n = 12)a
Age
55-59
60-61
62-64
65-66
67-69
.03
.22
.02
-.06
-.43
.33
-.10
-.29
.87
-.33*
-.61
-.85
-.69*
-1.33*
-.50
-.59*
-.77*
.27
.70*
.02
.04
.36*
.14
-.02
.19
.01
.30
-.31
-.10
-.18
-.70*
-.38
-.28
-.19
-.47
-.07
-.11
-.49*
-.18
-.80*
-.28*
-.78*
-.10
-.85*
-.31
-.71*
-.15
-.71*
-.11
-.12*
-.14
-.13
-.25
-.14
.10
-.70*
-.39*
.02
.06
-.26
-.34
.59
-.56
.11
-.84
-.13
-.06
-.22
.31
-.21*
.07
-.32
-.20*
-1.63*
-.17
-.54*
-.55
-.82
-.53*
-1.00*
-.25
-.67*
-1.27*
-1.54*
.23
.07
.14*
.14
-.10
-.14
-.37
-.06
-.04
-.29
-.37*
-.18
-.42
-.30*
-.02
-.65*
-.39*
-.51
.00
.55*
.00
.06
.15
-.36
-.25*
-.56*
.22
-.67*
-.16
-.78*
.03
.11
.00
-.07
.40
-.01
-.26
.33
.25
-.27
.20
-.37*
-.16
.12
.44
-.69
1.07
-.02
50-54
Men
Race/Ethnicity
Non-Hispanic Whites
African Americans
Hispanics
Education (years)
11
12-15
16+
Labor Force Status
In labor force (work limitation)
Not in labor force
Occupation (Work Limitation)
Professionals/managers
Laborers
Other workers
Women
Race/Ethnicity
Non-Hispanic Whites
African Americans
Hispanics
Education (years)
11
12-15
16+
Labor Force Status
In labor force (work limitation)
Not in labor force
Occupation (work limitation)
Professionals/managers
Laborers
Other workers
"Data are from 12 years of the National Health Interview Survey.
*p < .05.
TRENDS IN HEALTH AND ABILITY TO WORK
variables on work ability as well as the effect of controlling
for these variables on the strength of the time trend. Controlling for all of these characteristics standardizes for any
changes in the composition of the population (in age, race,
education, labor force participation, and occupation) that
might have occurred over the 12 years and indicates the effect of change over time with a standard population.
Persons in this age range have changed in their composition. For example, between 1982 and 1993, average years
of school completed rose from 11.6 to 12.5 for those in
their 50s and from 10.9 to 11.8 for those in their 60s. Labor
force participation also changed but the change was differential by sex. Men reported less participation in 1993 than
in 1982 (86% vs 83% for those in their 50s and 46% vs
41% for those in their 60s). The percent of women in the
labor force increased from 54% to 65% for those in their
50s and from 25% to 28% for those in their 60s. Among
persons in the labor force, there was a small increase in the
proportion in the "other" occupational category and a small
decrease in the proportion of laborers over the period.
We show the effect on being unable to work of each of
these compositional variables as well as the effect of reporting in a more recent year for the whole 50-69 year old sample in Table 3. First, we examine the average annual change
in each outcome with only age and sex controlled (Model
1) and then how this is affected by controlling for race and
ethnicity (Model 2), education (Model 3), and labor force
status (Model 4) or, in effect, standardizing for these sample characteristics. When age and sex are controlled, we
find a significant effect of years since 1982 such that the
relative likelihood of being unable to work is decreased by
2.1% every year (Table 3, Model 1). Controlling for race
(Model 2) has little effect on the time trend. When the composition of the population in terms of education is controlled (Model 3), however, the initial coefficient on time is
reduced by about two thirds to an annual reduction in risk
of 0.7, which is still significant. Thus, educational compositional change accounts for about two thirds of the relative
reduction in inability to work or work limitations over this
S35
time period. Controlling labor force status does not change
this result very much (Model 4). Although we do not show
the analogous regression results for the measure of work
limitation, being limited in ability to work is decreased annually by 1.7% with age and sex controlled and .5% when
education is introduced (results available upon request).
These results mean that most of the explanation for the
time trend in work ability is compositional—the changing
educational composition of this age group—but the decline
remains statistically significant even when education is
controlled, indicating that other factors were at work. Interaction terms between time and labor-force participation and
time and age are included in Model 5. Their significance in
Table 3 replicates the significance of the greater improvement in health at older ages and among those out of the
labor force as shown in Table 2.
Now we turn to subgroup differences in work ability.
Women are somewhat less likely to report inability to work.
We find that being female lowers the relative likelihood of
being unable to work by about 4% (before controlling for
labor-force status but with controls for education) and lowers the likelihood of being limited in work ability by 10%
(Model 3). On the other hand, being African American increases the likelihood (relative to that of non-Hispanic
Whites) of being unable to work by about half even when
education is controlled; this is a substantial reduction from
the 220% higher level for African Americans when education is not controlled. When education is controlled, the relative likelihood of Hispanics being unable to work is about
25% less than that of non-Hispanic Whites. Without education controlled, Hispanics are more likely than non-Hispanic
Whites to have work disability.
In Table 4, we include occupation along with the other
variables from Table 3 to examine limitation in work ability
for the working population. For this analysis, occupation is
divided into the three categories that roughly represent
white-collar professionals, blue-collar workers, and the
omitted category of sales and clerical workers. The significant time coefficient indicates that each year decreases the
Table 3. Logistic Regression Coefficients of Years Since 1982 and Other Predictors on Being Unable to Work for Respondents 50-69a
Model 1
Constant
Age
Female
Time"
Afr.American0
Hispanic0
Education
OutLF
Out LF X Time
Age X Time
-2 Log Likelihood
-.5.649***
0.068***
-0.023
-0.021***
[0.004]
[1.070]
[0.977]
[0.979]
186,223.27
Model 2: Model 1 +
Race/Ethnicity
Model 3: Model 2
+ Education
-5.869***
0.070***
-0.033**
-0.023***
0.789***
0.339***
-3.367***
0.059***
-0.039**
-0.007***
0.451***
-0.298**
-0.168***
[0.003]
[1.073]
[0.967]
[0.977]
[2.201]
[1.404]
184,274.61
[0.034]
[1.061]
[0.961]
[0.993]
[1.569]
[0.743]
[0.846]
175,835.63
Notes: Odds ratios are given in brackets. N = 226, 989. Out LF = Out of labor force.
"Data are from 12 years of the National Health Interview Survey.
"Time = Years Since 1982.
'White Non-Hispanics omitted.
*p < .05; **p < .01; ***p < .001.
Model 4: Model 3
+ Out of Labor Force
0.158
-0.028***
-0.638***
-0.009***
0.535***
-0.264***
-0.133***
3.176***
[1.171]
[0.973]
[0.528]
[0.991]
[1.708]
[0.768]
[0.875]
[23.96]
143,475.69
Model 5: Model 4
+ Interaction Terms
-1.292*** [0.275]
-0.006* [0.994]
-0.638*** [0.528]
0.211*** [1.235]
0.536*** [1.708]
-0.263*** [0.769]
-0.133*** [0.875]
3.309*** [27.34]
-0.019** [0.981]
-0.003*** [0.997]
143,352.79
S36
CRIMMINS ETAL.
Table 4. Logistic Regression Coefficients of Years Since 1982
and Other Predictors on Limitation in Ability to Work
Among Workers Aged 50-69a
Model 1
Constant
Age
Female
Time"
Afr.American0
Hispanic0
Education
Manager"1
Laborer11
Manager X Time
Laborer X Time
Age X Time
-2 Log Likelihood
Model 2
Model 3
-4.569*** [0.010] -3.549*** [0.029] -3.546*** [0.000]
0.045*** [1.046] 0.044*** [1.045] 0.044*** [1.045]
-0.089* [0.915] -0.114*** [0.892] -0.114*** [0.892]
[1.028] 0.027
-0.009*** [0.990] 0.027
[1.027]
-0.068* [0.934] -0.063
[0.939]
-0.512*** [0.599] -0.506*** [0.603]
-0.074*** [0.929] -0.074*** [0.928]
-0.206*** [0.814] -0.190*** [0.827]
-0.080** [0.923] -0.098
[0.907]
-0.002
[0.998]
0.003
[1.003]
-0.001 [0.999] -0.001
[0.999]
79,884.34
78,953.20
78,951.67
Notes: Odds ratios are given in backets. N = 121, 669.
"Data are from 12 years of the National Health Interview Survey.
"Time = Years Since 1982.
White Non-Hispanic s omitted.
"Other Workers omitted.
*p < .05; **p < .01; ***p < .001.
relative likelihood of limitation in work by about 1%; when
race, education, and occupation are controlled, this decrease disappears. This means that there was some small
annual average decrease in limitation among workers and it
can be explained by their changing composition. The difference between significant decline in work limitation among
workers shown in Table 4 and the insignificant decline
among workers shown in Table 2 undoubtedly arises from
the large N used in analysis for Table 4.
Predictably, relative to the omitted category of sales and
clerical workers, managers have a lowered risk of having
work limitation. Surprisingly, laborers also have a lower
level of overall limitation. Thus, the individual level analysis indicates that both managers and laborers have less
work limitation than those in the "other" category of workers. As expected, the interaction terms indicate no significant differences in time trends by occupation.
In order to better interpret the meaning of the statistical
results indicating a decrease over time in the likelihood that
one is unable to work and the size of the differentials across
subgroups, we estimate the probability that a person with
given characteristics would be unable to work in 1982 and
1993 using the results of individual-level models (Table 5).
First, because there are clear trends among those in their
60s and not in their 50s, and because this is the age range
surrounding the retirement years, we reestimate Table 3
(Models 1 and 3) for those in their 60s to use as the basis of
our estimates. The results of this reestimation are fairly
similar to those shown in Table 3, with the exception that
the size of the coefficient on time is greater (-.031 vs -.021
in Model 1; and -.019 vs -.007 in Model 3). Using coefficients from the model including just age, sex, and year
since 1982, we estimate the probability that a man and
woman would be unable to work at age 62, 65, 67, or 69 in
1982 or 1993 (Table 5, panels A and B). The decrease in the
estimated probability of inability to work is very dramatic,
Table 5. Estimated Probability of Being Unable to Work
at Two Dates at Specified Ages"
A. Men
Age 62
Age 65
Age 67
Age 69
B. Women
Age 62
Age 65
Age 67
Age 69
C. Non-Hispanic White Men
Age 62
10 yr education
16 yr education
Age 65
10 yr education
16 yr education
Age 67
10 yr education
16 yr education
Age 69
10 yr education
16 yr education
1982
1993
21.5
23.6
25.0
26.5
16.3
17.9
19.1
20.4
20.1
22.1
23.5
24.9
15.2
16.7
17.9
19.1
19.5
8.2
18.4
7.6
22.5
9.6
21.5
9.0
24.6
10.7
23.3
10.0
26.9
11.9
25.5
11.1
"Estimates based on logistic regression equations described in the Results section of this article.
an approximately 24% reduction in 11 years. Estimated inability to work at age 67 in 1993 was 19% for men and
18% for women. These dropped from 25% and 24%, respectively in 1982. Most importantly, this change indicates
that the work ability levels of those in their late 60s in the
mid-1990s are at the same level as those in their early 60s
in the early 1980s.
We have shown that a significant amount of the time
trend was due to changing educational composition; we can
also look at the estimated change among people with the
same education at the two dates. We could do this for any
gender, age, and education group and get similar change
over time, although each group would have a different level
of disability at the initial date. For illustrative purposes, we
show the estimated probability of being unable to work for a
non-Hispanic White man with either 10 or 16 years of education at four ages for 1982 and 1993. In each case, the drop
in the likelihood of being unable to work is about one percentage point for those with low education and slightly less
for those with a college education. Although the drop is
small, it indicates that with the same education level a 67year-old man in 1993 had a disability level similar to a 66year-old man in 1982. If this trend were to continue for another 11 years, the disability levels among 67-year-olds in
2004 would look like the disability levels among 65-yearolds in 1982 with the same educational level. The change
over time is significant, but the difference at any one point
in time between persons with high and low education is
much greater and indicates the reason that rising educational
levels have such a strong effect on population disability levels. For instance, a 62-year-old man with 10 years of educa-
TRENDS IN HEALTH AND ABILITY TO WORK
tion in 1993 has an 18.4% likelihood of being disabled,
which is more than twice that of a similarly aged man with a
college education. In fact, a 69-year-old man with a college
education is substantially less likely to be unable to work
than a 62-year-old man with 10 years of education.
In order to examine the differences in the probability of
being unable to work by gender and ethnicity at the most recent date, we estimate the probabilities of being unable to
work for men and women, African Americans, Hispanics, and
non-Hispanic Whites assuming each group has 10 years of
education in 1993. Whereas the difference between men and
women in inability to work is quite small, Hispanics are the
least likely to be disabled and African Americans the most
likely (Table 6). The likelihood of being disabled differs
markedly by race and ethnicity even when education is controlled. For instance, at age 65 among those with 10 years of
education, about one out of three African Americans, one out
of five non-Hispanic Whites, and one out of six Hispanics are
unable to work. Non-Hispanic White men and women at age
67 have estimated levels of disability lower than those of
African Americans at age 62. The lower level of Hispanic disability, once education is controlled, reflects the fact that the
Hispanic population has a substantial proportion of immigrants. Hispanics who are disabled early in life are unlikely to
come to the United States to work; some of those who become disabled are likely to return to their place of origin.
Prevalence of Disease
Although we have shown that a substantial portion of the
trend in work ability is related to the changing educational
composition of cohorts, we hypothesize that one of the
mechanisms through which education works to improve
population health is through a lower prevalence of disease
because lower disease levels are linked to higher education
(House et al., 1992). Time trends in the prevalence of a
number of major diseases and conditions, as well as trends
in the likelihood that these diseases cause inability to work,
are examined for the 1983-1993 period.
We are limited in the prevalence phase of the analysis to
the diseases about which respondents were queried. From
these we selected some of the major diseases and conditions
that are causes of disability, including arthritis, diabetes,
Table 6. Estimated Probability of Being Unable to Work in 1993
at Specified Age for Those With 10 Years of Education"
Age 62
African Americans
Hispanics
Non-Hispanic Whites
Age 65
African Americans
Hispanics
Non-Hispanic Whites
Age 67
African Americans
Hispanics
Non-Hispanic Whites
Men
Women
26.1
14.4
18.4
25.4
13.9
17.8
29.7
16.7
21.5
28.9
16.1
20.6
32.3
18.4
23.3
31.4
17.8
22.6
Estimates based on logistic regression equations described in the Results section of this article.
S37
mental disorders, musculoskeletal/orthopedic conditions,
cerebro/cardiovascular diseases, and respiratory diseases
(asthma, emphysema, and chronic bronchitis). These diseases account for 73% of the disability in this age group
during the 12-year period. Two of these disease categories
are much more prevalent than others: cerebro/cardiovascular
diseases and arthritis. Each of these diseases is present in
about 30% of 60-69-year-olds. Because we have found
more change in disability among those in their 60s than in
their 50s, we examine trends in disease presence for the subgroups of respondents in their 50s and 60s. For each disease,
the likelihood that a person has the disease is regressed on
age, sex, and years since 1983. This analysis begins at 1983
because the NCHS did not collect data on the causes of
work limitation in 1982. The odds ratios for significant coefficients on the variables representing the time trend or number of years since 1983 are presented in Table 7 (panel A).
Some disease groups are more prevalent in later years
and some are less prevalent. In both age groups, the relative
risk of cerebro/cardiovascular disease and arthritis declines
by 1-2% annually. The relative likelihood of diabetes increased in the older group by 3% per year; respiratory conditions increased in the younger group by 2% per year.
There was no trend in the prevalence of mental and musculoskeletal conditions in these age groups.
If the trends in disease prevalence are examined separately
for those in and out of the labor force (data not shown), the
trends for the subgroups are generally similar to those for the
combined population. The exceptions are that people in the
labor force in the 50-59 age range experience a declining
trend in only cerebro/cardiovascular disease but no trend in
arthritis. For those aged 60-69, cerebro/cardiovascular disease declines only for those out of the labor force.
We can also determine trends in the likelihood of reporting that a specified disease is a reported cause of work limitation (Table 7, panel B). Changes in this likelihood could
be an indicator of change in the prevalence of diseases, the
severity of diseases, the likelihood of work, or in the likelihood of finding work and disease incompatible (i.e., changing accommodation to health processes or job characteristics). For three diseases, there is a decrease in the likelihood
that the disease causes work limitation in both the younger
and the older group for arthritis, respiratory conditions, and
cerebro/cardiovascular diseases. For cerebro/cardiovascular
conditions and arthritis, this could mean that people not
only have fewer conditions, but that they have less serious
heart, vascular, and arthritis conditions than they did in the
past. On the other hand, among those in their 50s, there is
an increase in the likelihood of having a work-limiting condition caused by diabetes, a musculoskeletal condition, or a
mental disorder. Because we do not have evidence that the
prevalence of these diseases increased, this must mean that
either their severity increased, their compatibility with job
requirements lessened, or people are less willing to work
with these conditions. The fact that for respondents in their
50s respiratory conditions are less likely to be a cause of inability to work even though such conditions are becoming
more prevalent indicates that the increase in prevalence
may represent an increase in less severe cases. It is likely
that the increase in respiratory conditions results from a
S38
CRIMMINS ETAL
Table 7. Odds Ratios for Significant Logistic Regression Coefficients on Years Since 1983 Indicating Trends in Disease Prevalence
and Trends in Prevalence of Disease Causing Inability to Work (Panel A)
and Odds Ratios for Significant Coefficients on Years of Education and Years Since 1983 (Panel B)a
Dependent Variable
Prevalence of Disease/ Condition
Arthritis
Diabetes
Cerebro/cardiovascular diseases
Musculoskeletal conditions
Mental disorders
Respiratory diseases
N = -35,000
Prevalence of a Condition That Limits Ability to Work
Arthritis
Diabetes
Cerebro/cardiovascular diseases
Musculoskeletal conditions
Mental disorders
Respiratory diseases
N= -213,000
A Aged 50-59
Aged 60-69
Years
since 1983
Years
since 1983
B Aged 50-59
Education
Years
since 1983
.98
—
.98
—
—
.99
1.03
.99
—
—
.94
.89
.96
—
.64
.99
—
.98
—
—
.96
.93
.96
—
.66
—
1.04
—
—
—
1.02
—
.98
1.02
.95
—
.98
1.03
.95
1.03
1.05
.97
—
.97
—
—
.89
.84
.88
.91
.82
—
1.05
.96
1.04
1.06
.91
.88
.91
.93
.84
.98
1.02
.97
1.01
—
.98
.98
.88
—
.90
.98
C Aged 60-69
Education
Years
since 1983
a
Data are from 11 years of the National Health Interview Survey.
combination of an increase in asthma and a decrease in the
other potentially more serious respiratory conditions such
as emphysema (Reynolds, Crimmins, & Saito, 1998).
The estimated probability that a person of a specified age
and sex has a disease or a work limitation caused by a disease in a specified year can be computed using the equations
underlying the results shown in Table 7. When this is done
for arthritis and cerebro/cardiovascular conditions for 1983
and 1993, the decreases in the prevalence of arthritis and
cerebro/cardiovascular conditions for a 62-year-old man are
3% and 4%, respectively. During the same period, the estimated prevalence of arthritis dropped from 31% to 28%; the
estimated prevalence of cerebro/cardiovascular diseases
from 42% to 39%. This means that the prevalence of each of
these diseases declined by about 10% from its original level
over the period. The probability of having a limitation
caused by each of these diseases declined by 12% and 25%
respectively, or from 2.4% to 2.1% for arthritis and 9.1% to
6.7% for cerebro/cardiovascular conditions.
To address the issue of how the trend in disease prevalence
is related to educational change in the population, we control
for education in the equations that were the basis of the results reported for disease trends in Table 7. We then examine
both the relationship of education to the presence of disease
and how controlling for education affects the coefficients indicating the time trend (Table 7, panel B). With one exception, respondents with higher education levels are less likely
to report having a disease or being limited in work ability by a
disease. The only exception is that the prevalence of musculoskeletal disorders is not related to education in either age
group. The relative likelihood of having a cerebro/cardiovascular condition is decreased by 4% with every additional year
of education. The size of the effect on arthritis is similar. The
control for education reduces the coefficients on the time
trends in arthritis and cerebro/cardiovascular conditions to in-
significance among people in their 60s, indicating that it is educational compositional shifts that explain the time trend in
the prevalence of these diseases. Without educational change,
there would not have been a trend in the prevalence of these
diseases. The controls for education result in coefficients indicating significant increases in limitation from diabetes and
musculoskeletal conditions among individuals in their 60s.
This means that without educational change these diseases
would have increased. The other trends shown for people in
their 60s in Table 7, panel A, are not significantly affected by
the education controls.
DISCUSSION
The essential question raised by this article is whether
the increases in age eligibility for full retirement under Social Security were based on accurate assumptions about improving work ability. In order to answer this question, we
addressed three specific questions: (a) Is there evidence of
an improvement in ability to work in the 50-69 year age
group? (b) Is the trend the same for different subgroups of
the population? And (c) can the trend be explained by
changing population composition or is it due to changes in
the underlying health of the population after compositional
change is taken into account?
The evidence that self-reported ability to work has increased among persons older than 60 is clear. Whether
measured by inability in or limitation in ability to work,
over the period of 1982 to 1993, there is improvement reported in work ability. The improvement in work ability
during this period was significant, indicating a drop in work
inability of about 24%. The level of improvement observed
means that the legislated rise in age of full eligibility for
Social Security benefits should be more than compensated
for by the increase in the population's ability to work.
The trend toward improved ability to work appears to be
TRENDS IN HEALTH AND ABILITY TO WORK
similar for most subgroups of adults older than 60; the
trends do not differ by gender, education, or occupation.
Improvement in ability to work is most significant among
people who are out of the labor force. This must mean that
healthier people are leaving the labor force in more recent
years. Support for this was supplied by the finding that
among respondents in their 60s, the level of cardiovascular
disease declined among those who were out of the labor
force but not those who were in the labor force. Decrease in
limitation in work ability among people who work means
there is also some improvement in health among workers.
Part of the trend is related to compositional change in the
population. Individuals who are in their 60s in the 1990s
are more highly educated than those who were in their 60s
in the 1980s; the average educational level increased by
one year among those in their 60s across this period. Controlling for education removes the majority of the time
trend in work ability, all of it among workers. This means a
significant part of the trend is not related to changes in the
underlying health processes of the population but to compositional change. This is important in terms of how one
views the likelihood that health change will continue because the amount of compositional change varies from
decade to decade. In addition, the meaning of educational
changes may vary at different levels of education. Increases
in education among the now-older population may signify
major life differences in health behaviors and lifestyle.
These changes may not accompany subsequent increases in
educational attainment of the same size. However, the current difference between the educational level of people in
their 60s and those in their 50s of .7 years indicates that
there will continue to be educational increase among those
in their 60s for some time to come.
Changes in the prevalence of diseases are an indication
of the underlying mechanism through which population
composition changes health. Declines in cerebro/cardiovascular disease and arthritis prevalence and in these diseases
as causes of work limitation suggest both a decline in the
level and severity of these conditions, which are the major
causes of disability among the older population. The decline in the prevalence of these diseases in the population is
related to educational changes, and the lower levels of these
diseases are associated with improving education. However, educational change does not explain the lowered level
of reported work disability from these diseases.
We emphasize the importance of educational change in explaining trends in diseases and work ability because we feel
that education is an indicator of a set of lifelong circumstances that affect the health status of an individual. Educational level begins to affect health early in life in one's family
of origin and continues to affect one's health throughout
adulthood through its effect on health habits, the use of health
care, and exposure to health-affecting life situations such as
dangerous occupations or stress-inducing situations. Although
education and occupation are highly related, during this time
period we do not find significant shifts in the occupational
classification of this age group over the three broad categories
used here that would explain the time trend observed. In fact,
the occupation category that has increased slightly in size—
the "other" category, which includes service workers—is a
S39
relatively high disability category. Workers in this category
have the same level of work inability as laborers when education is not controlled and a higher level when education is
controlled. It is possible that if we used a different classification of occupation, we would find occupational change to be a
potential explanation for the time trend observed here. It is
also possible that there has been a general lessening of the demands of jobs in all categories that would make it increasingly possible to continue to work in the face of health problems. Such changes in job demands would also be compatible
with the reported improvement in ability to work.
Another potential explanation for trends in health is
changes in attitudes and policies toward working with disabilities or health problems. For instance, in 1990 the
Americans with Disabilities Act was passed and implemented. This may have encouraged people with disabilities
to define themselves increasingly as able to work and could
be related to the trend observed here. Changes in disability
policy are also a potential explanatory variable in any
change over time, although the direction of policy change
does not seem compatible with the time trend observed.
During the early 1980s, the enforcement of regulations was
tightened to make it more difficult to be declared work disabled; then, as often happens, these regulations were subsequently relaxed in the late 1980s (Bawden and Palmer,
1984; Schulz, 1995). These changes would seem to be a
countervailing force to the trends observed here.
Although there has been improvement among people in
their 60s in nearly all ethnic-gender subgroups of the population, there are still differential abilities to work reported
by gender, race/ethnicity, education and occupation. This
means that subgroups are currently affected quite differentially by the rules for Social Security age of eligibility and
this differential is unlikely to change. We have shown that a
White man at age 62 with 10 years of education has a level
of work inability more than 60% higher than a man with
the same characteristics who has a college education. Similarly, African American men are about 40% more likely to
report inability to work than non-Hispanic White men with
the same level of education. These differences in work ability by socioeconomic status are much larger than differences between ages 65 and 67 for all groups and indicate
that Social Security policy will have to continue to consider
the welfare of the significant number of persons who are
unable to work to normal retirement age.
Respondents in their 50s did not experience improvement
in work ability even though this age group also changed in
educational level. For people in their 50s, there is evidence
of a countervailing force in the increased likelihood of reporting certain diseases as work limiting. This could be due
to either changes in jobs, benefits, or attitudes. These findings suggest caution must be used in projecting current
trends into the future.
ACKNOWLEDGMENTS
This article was prepared with support from Social Security Administration Grant No. 10-P-98354-9-01 and NIA Grants No. T32-A6-00037 and
R01 AG11235. An earlier version of this article was presented at the
November 1995 Annual Meeting of the Gerontological Society of America, Los Angeles, CA.
S40
CRIMMINS ETAL.
Address correspondence to Dr. Eileen M. Crimmins, Edna M. Jones
Professor of Gerontology, Andrus Gerontology Center, University of
Southern California, Los Angeles, CA 90089-0191. E-mail: crimmin@
almaak.usc.edu
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Received April 27, 1998
Accepted August 7, 1998